"""
Move Sprite by Angle

Simple program to show basic sprite usage.

Artwork from https://kenney.nl

If Python and Arcade are installed, this example can be run from the command line with:
python -m arcade.examples.sprite_move_angle


根据角度移动精灵

展示简易精灵的用法

"""
import arcade
import math

SPRITE_SCALING = 0.5

WINDOW_WIDTH = 1280
WINDOW_HEIGHT = 720
WINDOW_TITLE = "Move Sprite by Angle Example"

MOVEMENT_SPEED = 5
ANGLE_SPEED = 5


class Player(arcade.Sprite):
    """ Player class """

    def __init__(self, image, scale):
        """ Set up the player """

        # Call the parent init
        # 初始化玩家精灵（包括图片和缩放比例）
        super().__init__(image, scale=scale)

        # Create a variable to hold our speed. 'angle' is created by the parent
        # 玩家初始速度为0。角度在父级参数中已包含
        self.speed = 0

    def update(self, delta_time: float = 1/60):
        # Rotate the ship
        # 根据change_angle旋转角度
        self.angle += self.change_angle

        # Convert angle in degrees to radians.
        # 将角度转化为弧度
        angle_rad = math.radians(self.angle)

        # Use math to find our change based on our speed and angle
        # 计算新的delta_x和delta_y，进而变更玩家坐标
        self.center_x += self.speed * math.sin(angle_rad)
        self.center_y += self.speed * math.cos(angle_rad)


class GameView(arcade.View):
    """
    Main application class.
    主应用类
    """

    def __init__(self):
        """
        Initializer
        """

        # Call the parent class initializer
        super().__init__()

        # Variables that will hold sprite lists
        # 声明玩家列表
        self.player_list = None

        # Set up the player info
        # 声明玩家精灵
        self.player_sprite = None

        # Set the background color
        # 配置背景色
        self.background_color = arcade.color.BLACK

    def setup(self):
        """ Set up the game and initialize the variables. """

        # Sprite lists
        # 初始化精灵列表
        self.player_list = arcade.SpriteList()

        # Set up the player
        # 初始化玩家精灵，包括精灵的xy坐标，并将玩家精灵放到精灵列表中
        self.player_sprite = Player(":resources:images/space_shooter/playerShip1_orange.png",
                                    SPRITE_SCALING)
        self.player_sprite.center_x = WINDOW_WIDTH / 2
        self.player_sprite.center_y = WINDOW_HEIGHT / 2
        self.player_list.append(self.player_sprite)

    def on_draw(self):
        """
        Render the screen.
        """

        # This command has to happen before we start drawing
        self.clear()

        # Draw all the sprites.
        # 绘画精灵列表
        self.player_list.draw()

    def on_update(self, delta_time):
        """ Movement and game logic """

        # Call update on all sprites (The sprites don't do much in this
        # example though.)
        # 根据时间段更新玩家列表（实际没有用到）
        self.player_list.update(delta_time)

    def on_key_press(self, key, modifiers):
        """Called whenever a key is pressed. """

        # Forward/back
        # 通过上下控制速度
        if key == arcade.key.UP:
            self.player_sprite.speed = MOVEMENT_SPEED
        elif key == arcade.key.DOWN:
            self.player_sprite.speed = -MOVEMENT_SPEED

        # Rotate left/right
        # 通过左右控制角度
        elif key == arcade.key.LEFT:
            self.player_sprite.change_angle = -ANGLE_SPEED
        elif key == arcade.key.RIGHT:
            self.player_sprite.change_angle = ANGLE_SPEED

    def on_key_release(self, key, modifiers):
        """Called when the user releases a key. """
        # 释放按键后，重置变更速度和变更角度
        if key == arcade.key.UP or key == arcade.key.DOWN:
            self.player_sprite.speed = 0
        elif key == arcade.key.LEFT or key == arcade.key.RIGHT:
            self.player_sprite.change_angle = 0


def main():
    """ Main function """
    # Create a window class. This is what actually shows up on screen
    window = arcade.Window(WINDOW_WIDTH, WINDOW_HEIGHT, WINDOW_TITLE)

    # Create and setup the GameView
    game = GameView()
    game.setup()

    # Show GameView on screen
    window.show_view(game)

    # Start the arcade game loop
    arcade.run()


if __name__ == "__main__":
    main()